Deriving natural classes in phonology

It is one of the most basic generalizations in phonology that only certain sets of sounds pattern together in phonological processes. These sets are referred to as natural classes. This paper develops a new analysis of the natural class generalization, formulated in terms of Optimality Theory. It is shown that natural classes derive from the nature of the set of markedness constraints. For example, sounds can pattern together as a natural class if they violate markedness constraints in the same environment, so given constraints ∗XA and ∗XB, A and B can form a natural class. As a result the range of possible natural classes depends on the inventory of constraints, not on the feature set. This analysis is shown to have empirical advantages over the standard account according to which natural classes are characterized purely in terms of features.